What does "three tracks with bundles are needed to orient the floor" mean?
In order to create the floor you have to solve the clip first. bundles are basically solve data for the track. Your error is probably caused by unsolved/incorrectly solved tracks.

From the wiki:


  Bundles makes sense after solving the movie clip, and it works in the following way: the solved position of each track gets projected
  back to the movie clip and displayed as a small point. The color of
  the point depends on the distance between the projected coordinate and
  the original coordinate: if they are close enough, the point is green,
  otherwise it'll be red. This helps to find tracks which weren't solved
  nicely and need to be tweaked.